The present invention relates to beverage dispensing systems, and in particular, to systems for dispensing beverages which contain dissolved gases (e.g., carbonated beverages such as beer or soda), which are stored in kegs, and dispensed from faucets at locations more or less remote from the keg storage location.
Systems for the dispensing of beer are especially problematic. In a typical bar installation, the beer kegs are stored in a cooler in a basement or back room, vertically and/or horizontally remote from the dispensing location (bar). A number of beverage transport tubes extend from the kegs in the cooler to the bar, to a dispensing device to which the faucet or faucets are attached. A number of other tubes, carrying a coolant (glycol), are placed in a circuit from the cooler, substantially parallel to the beverage transport tubes, all the way to the faucets, and back to the cooler, so that the beer and the faucets are cooled. The two sets of tubes are typically encased together in a temperature isolating enclosure, and the assembly is often referred to as a "python".
The motive force which causes the beer to flow in such a system is pressurized gas. Most relatively small systems utilize carbon dioxide, which is supplied from pressurized cylinders. A pressure regulator, between the cylinder and the beer kegs, is nominally used to control the amount of pressure applied to the beer. In larger, or more extended systems, a mixture of gases (air and carbon dioxide) may be used, requiring the use of a compressor. Such mixed gases are also used when the pressure required in a carbon dioxide system, just to make the beer move, is so great that gas absorption will take place readily (as described in further detail hereinafter). Such mixed gas systems are complex and expensive.
A typical beer keg is configured so that the tube, through which the beer is withdrawn from the keg, has its opening adjacent the bottom of the keg. The pressurizing gas is inletted into the keg through an opening in the top of the keg, so that the pressurizing gas pushes "down" on the beer.
Optimally, a beer dispensing set-up, once established, will provide the cold beer at a desired flow rate of approximately one gallon per minute, with the beer leaving the faucet in a continuous, substantially completely liquid state. In order for a beer to "run" properly, the system must be configured so as to place a certain amount of "back" pressure (that is, resistance pressure) in the lines, when running. A typical desired range of back pressure is between nine and twenty-four pounds per square inch. However, each beer dispensing installation is an individual set-up, which must be calculated and laid out according to the customer's needs, and the structural limitations (e.g., run length) of the site.
It is often the situation that a dispensing set-up may often, almost immediately begin to have performance which departs significantly from that anticipated when the set-up is first installed. The back pressure will be or become substantially lower than anticipated, prompting the proprietor to raise the pressure of the propellant gas. This may have the result of producing an "over-rebound", in that the beer will then have too much propellant pressure, thus producing foam. Variations in the keg volume, or in the line or cooler temperature, may also adversely affect the flow of the beer, prompting the operator to attempt a quick solution by increasing the gas pressure.
Foam occurs when the beer is agitated, or when the beer passes quickly through a region of sudden, drastic pressure drop. In a typical beer dispensing faucet, the flow passageway widens suddenly where it joins the valve portion of the faucet. This area is often referred to as the "bellmouth" It is believed that if the beer is under too high a pressure as it approaches the bellmouth, the sudden increase in available volume upon entering the bellmouth so drastically lowers the pressure on the beer that the carbon dioxide which is dissolved in the beer comes out of solution, producing foam. Excess foam is perhaps the leading cause of wasted beer, and thus lost profits, from which a proprietor may suffer.
An additional problem which may result from the application of excessive propellant pressure (particularly carbon dioxide) applied to the beer kegs is that of absorption of the propellant gas into the beer. Once a particular keg has been tapped, and the propellant pressure is applied, the pressure is continuously applied, night and day, even when the establishment is closed. Over time, if the pressure is too great, and the consumption of the beer is slow enough, the beer will absorb more than a tolerable amount of gas, and the taste of the beer will be adversely affected, thus causing a particular keg to have to be changed prematurely, leading to additional waste.
The performance of a particular dispensing set-up may also be affected by the brand of beer which is being delivered. Some lighter beers are "fragile" and tend to break up into foam even over short distances, due to the pressure required to make them flow at all. Low alcohol beers are also difficult to make "run", that is, flow without foaming, since, by their nature, they do not hold carbon dioxide in solution well.
In addition to such "immediate" changes to performance, the performance of a dispensing set-up may degrade over time as a result of a number of factors. For example, the functioning of the cooler in which the kegs are stored may degrade, raising the beer temperature slightly, and increasing its propensity to break up. An increase of only 2.degree.-3.degree. F., insufficient to be otherwise noticed by a consumer, could lead to substantial losses to foaming. Damage to the transportation piping, caused by the application of caustic materials during required periodic cleaning, also can affect the performance of the dispensing system.
It is believed that such various difficulties as may arise in the operation of a delivery system may be remedied if there would be some way to elevate the back pressure (not the applied pressure) while slowing the volumetric flow rate, so as to control the tendency of the beer to foam.
Because the piping for a beer delivery system must be insulated along its route in order to prevent losses due to the absorption of heat, once a system has been installed, it may be unreasonably costly to gain access to the system components in order to modify the existing delivery system to add in back pressure, typically by adding length to the piping. Physical obstructions or flow diverters such as baffles, and the like, cannot be added mid-stream into the flow, as any such items may serve as sites for bubble nucleation, leading to foaming. Additional back pressure can thus only practically be added at the delivery end of the system, at the faucet.
Prior art attempts at providing apparatus for adding back pressure have typically comprised the integration of a flow regulator into the faucet, in the form of a piston, which is axially movable in the direction of the shank of the faucet. This piston may be covered with an elastomeric sheath so as present a relatively smooth surface to the beer flow, to prevent the formation of foam. The free end of the piston, which points upstream, may be formed as a tapered cylinder, or even as a cone, and will be actuated by a lever on the outside of the faucet. When actuated, the piston will move, so as to obstruct a greater or lesser amount of the flow passageway in the shank, to increase or decrease the effective cross-sectional area of the flow passageway. Faucets incorporating such devices are manufactured or have been manufactured in the past by such firms as Cornelius in Anoka, Minn., and Perlick in Milwaukee, Wis.
Faucets incorporating such devices have apparently generally not proved popular, though. The piston assembly adds to the physical dimensions of the faucet, by greatly lengthening the shank portion, making such faucets too awkward, bulky, or simply too long to fit in many applications.
It is, accordingly, an object of the present invention, to provide an apparatus for controlling foaming and flowrate in a pressurized beverage dispensing system, such as a beer tapping system.
Another object of the invention is to provide an apparatus for controlling foaming, while otherwise improving performance of a beer tapping system, by providing additional back pressure to the system to "balance" the overall system.
A further object of the invention is provide such a foam control apparatus which additionally regulates the flowrate of the beverage being dispensed to additionally control and substantially preclude break up of the beverage during dispensing.
Still another object of the invention is to provide such a foam control device which may be readily added to a dispensing system, after the system has been originally installed, without requiring substantial disassembly of the system, or causing potentially destructive or disruptive uncovering of enclosed, sealed components of the system.
Yet still another object of the invention is to provide an apparatus for controlling foaming in beverage dispensing systems which may be readily and inexpensively fabricated and installed.
These and other objects of the invention will become apparent in light of the present specification, claims and drawings.